Electronic control system for hydraulic motor



Jan. 15, 1957 c. E. ADAMS ET AL 2,777,425

ELECTRONIC CONTROL SYSTEM FOR HYDRAULIC MOTOR Filed Sept. 16, 1953 O l I3O 3 24 f? 34- Y 3 I I 25x 27] so Z O 57 M NH] fiA WJV Xx I 661 FlG.-l11454! 45 I! i 5| as 70: ea l 7 I 52 1 41 A.C.LINE$ INVENTORIS CECIL E.ADAMS BY KENNETH QGOODMAN X MA/MWF ELECTRONIC CONTROL SYSTEM Fol:

HYDRAULIC MOTOR Cecil E. Adams and Kenneth C. Goodman, Columbus, Ohio,assignors, by mesne assignments, to American Brake Shoe Company, NewYork, N. Y., a corporafion of Delaware Application September 16, 1953,Serial No. 380,578

12 Claims. (Cl. 121-38) ing electrically operated or electro-responsiveelements and has as an object the provision of an electronic controlsystem by which certain desirable features of hydraulic motor operationwill be secured.

It is an object of the invention to provide fluidpressure operatedapparatus having an electronic control system which will cause a rain orother movable element of a fluid motor, to continue to move in a desireddirection, after the motion has been initiated, until a predetermineddistance has been traversed or a resistance of pr'edete'rmined force isencountered then automatically reverse and return to the starting point.

It is an object or this invention to provide control mechanism for ahydraulically operated device which control mechanism will operatesubstantially independently or the hydraulic system of the device, inthat-it will: only require "a iminilrlum'of the hydraulic power foritsoper'ation and yet it will be responsive to e'fiec't certaindesiredoperations when predetermin d conditionsexist in the hydraulicsystem.

More s ecifically, it is an object of this invention to provide :anelectronic control systenifor a hydraulically operated device, such as apress; which system- M1!" cause the ram ofthe press to advance to andexert a predetermined force on an: article disposed in its athand thenbe retracted to its initial'or s'ta'r'ting 'po'si ti'oi'r.

A further object or the invention is' to provide an elec- 'troniccontrolsystem for a hydrauliepre'ss'; the system having means for generatinganelectrical current when the ram is advancing, h cur-rent being employedto maintain the new of responsive -'dev-i'ce which, in turn,niain't'ains the fl'oW'of hydraulic fluid to the rain untilapredetermined pressure is reached after which the system ope-rates t'otz'ausfe the ram to retract, the control system being": devoid ofressure'switohesror an 'directconnection With the hydraulic system of thepress,

A still further bject" or the invention isto proviiie-a hydraulic presswith an eleetr'o'nic control systenr having coil through'which amagnetized element is moved by thermi to -generatean ele iic currentwhich 'isielfl'pldyd to liee an electronic switch," such a's iathyratron-tiib'e, in' condition to -direct a no rating current from" asource to a soierroid' valve tires holding the valvein position todirect fluid pressure from a"'SOHI e to a ptirtin the" cylinder ofthepress to-cause'the rain to contirtnei'ts advancing movement,the'c'e'ss'ati'on of rain movement, due" to reaching. the end of itsstroke or engagingan obstruction which offers sutficieht resistance tocause therelief valve rim the=liydraulic-systeni to open; serving toidiscontinue the current generation and interrupt the new or currentUnited States Patent-O 2,777,425 Patented Jan; 15, i957 to the solenoidvalve permitting the same to shift to a position in which fluid pressurewill be directed to a differ'ent port in the press cylinder to cause therain to return to a starting position. i

Another object of the invention is to provide a hydraulie press orsimilar device with an electrical control systern having a motionsensing device which is responsive to the movement of the press ram tomaintain a relay in the control system in a closed or current supplyingcondition so that an electro' responsive control valve for the to thepress ram, the hydrauliesystern' for the press having a relief valvewhich by-pas'ses the fluid to the reservoir,

when the press ram meets a predetermined resistance, and permits therain to stop moving; the motion sensing device then permits the relay toassume an open position and the control valve will shiftto a differentosition to cause reverse movement of the press" ram. The effect securedbythe control is that known in the tradeas ressure reversal althoughpressure responsive switches or the like srenot em 1oyed.-

Further'objectsand advantages of the resent invention will be apparentfrom the following description, reference beinghad t0 the accom anyingdrawings wherein apieferre'd fornroi embodiment of the invention is'clearly Shown.

In the drawings: v Thesole figurein the drawing shows a combinationdiagrammatic view" or the Hydraulic apparatus and systent forming a partthereof and the electronic control system; i g

In carrying out the invention, use is made, in the form or" theinvention: illustrt'tte'd; or a hydraulic ress. The control system is"adaptable" to other types of hydraulic devices; the press shown beingselected for illustrative pur oses onl Thispress'includes source orfluid ressure 20' having a r-eservoir' 21-, a pum 22, and a reliefvalve- 2 3;-*a fluid line leading from thereservoir tothe pump, from thelat-fer to the relief valve,- and from this 'nieinber toa control valveof the" reversing t-y'pe' indicated from the relief v'alveba'ck tothereservoirto conduct fluid operating currentto" an eleet'r'oinch andtank orts 31 rrorrr the pump to the'la'tter when the relief valve opensdueto the pressure in the source increasing beyond that for which therelief valve has been adjusted.

The reversin valve 24' cone-01s the" flow" of fluid from the pressuresource to areversible fluid motor, indicated generallyby the numeral25', which, in this instance, has

been illustrated asa c linder-2s and' isten 27', a ra n is projectingfrom the piston, The reversingwalve 24 iiicl'nde's a body- 30 havinginlet, forward and ev se dylto135, respectively. The inlet port 31receives fluid. directly from the p essure source.

, The forward and reverse cylinder ports are connected by lines wit-l'ltire-upper and lower'ends'of the cylinder 26 while the tank ports 34 and35 are suitably connected with the reservoir 21. Valve body 30? receivesa spool 'rnefr'riber which isprovi'cle'd with spacedheadsfii' and 38 soarranged to form grooves which establish cont"- 'riilinica'tion betweencertain of' the portslin" the body dejpending up'on the longitudinalposition of the spool. This spit-o1 is=urged in'one directionby a coilspring ift'o'cause the grooves inthe sp'ool'to establish communicationbetween the inlet port' 31 and the reverse nioto'r port" 33.

the spool is in the position to establish this cornriiunication, theports'32- and 34 will also" be connected and fluid froni tliepressilresource'will'fiow'into the lower end of the-power cylinder to'cause'tlie'p'istoh 27 to' move in anupward or reverse direction; In so moving;the pistoir'will discharge-fluid from the upper end or the pervertslindenthrough orts 32ahd 34 totli'e reservoir.

As the piston nears the upper end of its travel, a bar 41 carried by theram will engage a collar 42 provided on an extension 43 of the valvespool and will move the valve spool, in opposition to the spring 40, toa position wherein the fluid pressure from the source will be directedinto the tank port 35 from which it will flow to the reservoir 21. Atthis time, the ram will stop in its elevated or retracted position.

The reversing valve is provided with a solenoid 44 for moving the spoolto a further extent in opposition to the spring 40. When the spool ismoved by the solenoid, communication will be established between theinlet port 31 and the upper end of the power cylinder 26. Fluid from thepressure source will then flow to the upper end of the power cylinderand will cause the piston and the ram to advance or move in a downwarddirection. Fluid displaced by the piston will be exhausted from thelower end of the power cylinder through ports 33 and 35 to the reservoir21. In the event the ram should meet an obstruction which offerssufficient resistance to prevent further movement thereof, the reliefvalve 23 will open to permit fluid from the pump to be by-passed back tothe reservoir. At this time, the ram will be exerting the force forwhich the relief valve has previously been adjusted.

The invention herein relates to a control mechanism for the reversiblefluid motor. The solenoid 44 forms a part of this control mechanism. Aspointed out in the objects, a feature of this invention is to secure areversal of the min when a pressure, determined by .therelief valve 23,has been reached in the portions of the hydraulic system communicatingwith the upper end of the power cylinder; in other words, when the ramis exerting a predetermined force. It is also a feature of the inventionto secure this reversal without the use of pressure switches. Theelectrical control system, illustrated in the drawing, makes thisoperation possible.

This control system includes relay mechanisms for controlling the flowof current to the solenoid 44. A plurality of sections are included inthe relay mechanisms, one of the sections, designated by the numeral 45,having a field coil 46, one end of which is connected with one of thecurrent supply lines 47 while the other is connected with line 48, thisline leading to one side of a push-button switch mechanism indicated bythe numeral 50. The other side of this switch mechanism is connected bya line 51 with the other current supply lead 52. Line 51 also contains alimit switch 53 which is disposed in the path of the bar 41 carried bythe ram. When the ram is fully retracted, switch 53 will be closed toprovide for current flow when the switch 50 is operated. This switch maybe manually actuated or actuated in any other manner depending upon thedesires of the manufacturer. When switch 50 is closed while the ram isfully retracted, current flow through coil 46 will be initiated. Whencoil 46 is energized, it will elfect the closing of two switchescontrolled by the armature of the relay. One of the switches, designatedby the numeral 54 controls the flow of current to the solenoid 44 and,when coil 46 is energized, switch 54 will be closed to provide for theflow of current to the coil 44. The energization of this coil causesspool 36 to move, as previously described, in opposition to the spring40 to a position in which the inlet port 31 of the valve 24 is connectedwith the forward cylinder port 32 and fluid from the pressure sourcewill be directed to the upper end of the power cylinder to cause the ramto advance. It will be obvious that initial movement of the ram willcause the bar 41 to move away from switch 53. Since this switch is ofthe normally open type, the movement of the bar will permit the switchto open interrupting current flow to the control switch 50. The flow ofcurrent to the relay coil 46 will not be interrupted, however, due tothe provision of the relay section 55 and a motion sensitive mechanismdesignated generally by the numeral 56.

The control mechanism also includes an electronic switch 57 which may beof any suitable type, a thyratron tube having been found to perform theoperation desired satisfactorily. The motion sensing mechanism has acoil 58 stationarily supported adjacent the power cylinder and havingits ends connected by lines 60 and 61 with one element in the tube 57and with the control mechanism 62 for the tube, this control mechanismbeing connected with lead 52 of the power source. The motion sensingmechanism also includes a permanent magnet 63 which is dis posed formovement in the coil 58 and is connected with the ram by the bar 41.When the ram moves in a for ward direction, the magnet 63 moves in thecoil 58 cansing a current to be generated which is conducted to theelement in the tube 57. When this element is excited in this manner,current will flow from the supply source 47,

52 to the field coil 64 of the second section of the relay mechanism.When coil 64 is energized, a switch arm 65 forming part of this relaywill be moved to a position to close the circuit for the coil 46. Inthis manner, coil 46 will be energized to maintain the switch 54 incondition to continue the flow of current to the solenoid 44. It will beobvious that, as long as the ram is moving, solenoid 44 will hold thespool 36 in position to connect the upper end of the power cylinder withthe source of fluid pressure. The switch including arm 65 is arranged inseries with a second switch 66 forming a part of the relay mechanism 45.

When the ram meets an obstruction which will offer suflicient resistanceto interrupt the movement of the ram, the relief valve 23 will open tobypass fluid from the pump directly back to the reservoir. At this time,the ram will be exerting the maximum force for which the relief valvehas previously been set. Due to the interruption of the forward motionof the ram, the motion sensing mechanism 56 will cease to generatecurrent and the tube 57 will no longer permit current to flow to thecoil 64. Arm 65 will then move to a switch-open position permitting coil46 to be de-energized. When this condition exists, switch 54 will openand solenoid 44 will be de-energized. Spring 40 will then move the valvespool to the position in which the source of fluid pressure will bedirected to the lower end of the power cylinder. As previouslydescribed, the direction of fluid to this end of the power cylindercauses the ram to move upward, which motion will normally be continueduntil the bar 41 engages the collar 42 and shifts the valve spool to aposition in which the fluid pressure source will be connected with thereservoir. The ram will then come to rest. As previously pointed out,when the .ramreaches this position, switch 53 will be closed and a newcycle of operation of the ram may again be initiated through the closingof switch 50.

In some instances, it may be desirable to cause the cycle of ramoperation to be automatically repeated. To provide for this type ofoperation, a selector switch 67 has been included. In this positionshown, switch 67 is ineffective and the initiation of a cycle ofoperation will be controlled solely by the switch 50. If switch 67 ismoved into engagement with contact 68, the switch 67 will then be inparallel with switch 50 and, when switch 53 is closed due to thecomplete retraction of the ram, coil 46 will be automatically energizedwithout the closing of switch 50 to initiate a new cycle of ramoperation. These cycles will be repeated as long as contact 68 isengaged.

In some instances, it has been found desirable to cause the ram toresume forward movement prior to the completion of a cycle of operation;in other words, before the switch 53 is closed. When this form ofoperation is desired, the switch arm 67 is moved into engagement withcontact 70 and switch 53 is then shunted out. It will be ob served that,at this time, switch 50 may be closed when desired to complete thecircuit for the coil 46 and the activation of the solenoid 44. If theram is moving in a reverse direction at this time, the spool 36 will beoperated to interrupt the reverse movement and cause the ram to move ina forward direction. If the switch 50 is held in a closed position, theram will continue to move downward liv'ivgide i. wane m int in'a new of,electrical energy to sai ll t 'cre p nsi ve m ans to. hold the same"inhcsitio il au e the" continuat n the opera ion of said flui g in a done direction, sai i,rnbv m t'resp i iv m l 'git re uce thefi w ofelectrical en y sai eleg responsive means when the'movernent of theveble e men of a d'fluid motcrfceas i a d me n fQrQa'ctii 'n'g' saidreversing 'valve' to cause reverse operation of said motor when theflow, of electrical"energy 1. sai echo-responsive means is reduced 2;Central mechanism fo hy au c ppa a lth' ,type" liaving' a reversible'fluid motor with a' movable e1 efnt, a unce of fluidpressure and .al evei' i gval l bet een said pressure so r vand said'flui lmo r.cenprisingelectroiresponsive means for actua rig" said valve tocauSef'the operation of said fluid motor in one irection; relay meansforfcbntrolling" the flower electric energytrom'a source to saidelectro-responsive means; i

and means responsive to the movement of the movable element ofsaid-fluid motor whenoperating in said one direction to energize saidrelay means anddirect electric energy to said" electro-responsive meansto hold said reversing-valve in position to continue'the operation ofsaid fluid motor in said one direction;

3. Control mechanism for hydraulic apparatus of the type having areversible fluid motor with a movable element, a source offluid-pressure and a reversing valve be i eensaid pre sure sourcend'said-fl d metor eomprising electro-responsiveimeans for actuatingsaid valve to cause the operation of said fluid motor in one direction;relay means for controlling the flow of electric energy from a source tosaid electro-responsive means; switch means for initially energizingsaid relay means to start the flow of electric energy to saidelectro-responsive means and the operation of said fluid motor in saidone direction; and means responsive to the movement of the movableelement of said fluid motor when operating in said one direction to keepsaid relay means energized during such operation of the motorirrespective of the condition of said switch means.

4. Control mechanism for hydraulic apparatus of the type having areversible fluid motor with a movable element, a source of fluidpressure and a reversing valve between said pressure source and saidfluid motor comprising electro-responsive means for actuating said valveto cause the operation of said fluid motor in one direction; relay meansfor controlling the flow of electric energy from a source to saidelectro-responsive means; switch means for initially energizing saidrelay means to start the flow of electric energy to saidelectro-responsive means and the operation of said fluid motor in saidone direction; means responsive to the movement of the movable elementof said fluid motor when operating in said one direction to keep saidrelay means energized during such,

operation of the motor irrespective of the condition of said switchmeans; and additional switch means for n of sai f ui motor when ope atng in aii o relate" Q then mentioned switch-meanseffective only ARM?tefniinh 5 ageof operatioiiofrsaid fluidmotor. ntrol mechanism 'forhydraulic apparatus of the .t'yp viiigfa reversible fluid vniotorfhavinga movable elein'ntia source of'fl dpressure land a .reversing'valve bet1" 'essuresour'celandsaid flnid'motor com- V pensive means,for',actuatiiig.-said valve I. 'cal js 'th op at in" of said fluidm'otoi in one direcel means for controlling the flow of electric energytrams source to said electro-respion'siv'e means; switch meansffor iallyenergizing said relay mea s to e' ow 'ojf fe'lectric'energy' to (saidelectroaesbonsive and "the operan ni of said fluid motor in said oneean's' responsive to-the 'movementfo'f the mavable elementjofis'aidfluid motor whenioperatinginsaid one direction to keep said relaymeanslenerg'ize'd during such operation o'fthe' motorirrespect'ive ofthe condition of sa'idfswitch means; and additional" switch "meansatranged ii'r' series with: said "first-mentioned switch means, saidadditional switch means' beingoperated in part by said fluid motor'torender said first-mentioned switch means'etiective'fomy at apredetermined stage of operation off said fluid motor:

' 6." Gontr'ol'mechanism for hydraulic apparatus o'f 'the type havin giareversible fluid motor having a movable 'elemfen'ga source of fluidpressure anda reversing valve between said"'pressure source and'saidfluid motor compi isingfelectro responsivemeans "for actuating saidvalve to 'c'a'use'the' operation of said fluid motor 'inone direction;

relay means for controlling the flow of electric energy from aiso'urceto said electro-responsive means; switch meanstor initially energizingsaid relay means tostart th'e'flowfo'f'eleetric energy to said electroresponsive means andthe' operation of said fluid motor in said onedirec-"tion; means responsive to the'movernent of the movable element of" saidfluid motor'when operating in said one direction tokeep'said relay meansenergized during such operation of the'motor irrespective of thecondition of said switch me ns; additional switch means arranged inserieswith'saidfirst-mentioned switchmeans said additional switch meansbeing operated in part by said fluid motorto render said'first-mentionedswitch means ejfiective only a'ta predetermined stage of operation ofsaid fluid motor; and a selectively operable switch meansarranged'in'parallelwith said additional switch means.

7. Control mechanism for hydraulic apparatus of the type having areversible fluid motor with a movable element, a source of'fluidpressure and a reversing valve between said pressure source and saidfluid motor comprising electro-responsive means for actuating said valveto cause the operation of said fluid motor in one direction; relay meansfor controlling the flow of electric energy from a source to saidelectro-responsive means; switch means for initially energizing saidrelay means to start the flow of electric energy to saidelectro-responsive means and the operation of said fluid motor in saidone direction; means responsive to the movement of the movable elementof said fluid motor when operating in said one direction to keep saidrelay means energized during such operation of the motor irrespective ofthe condition of said switch means; additional switch means arranged inseries with said first-mentioned switch means, said additional switchmeans being operated in part by said fluid motor to render saidfirst-mentioned switch means efiective only at a predetermined stage ofoperation of said fluid motor; and a third switch means having twoefiective positions, one of which places said third switch in parallelwith said additional switch means and the other position placing saidthird switch in parallel with said firstmentioned switch means.

8. Control mechanism for hydraulic apparatus of the type having areversible fluid motor with a movable element, at source of fluidpressure and a reversing valve between said pressure source and saidfluid motor comprising electro-responsive means for actuating said valveto cause the operation of said fluid motor in one direction; relay meansfor controlling the flow of electric energy from a source to saidelectro-responsive means; switch means connected with said relay meansand operative to initially energize said relay to start the flow ofelectric energy to said electro-responsivemeans and the operation ofsaid fluid motor in said one direction; and a second electronic switchmeans responsive to the move- 'ment of the movable element of said fluidmotor when operating in said one direction to keep said relay meansenergized during such operation of the motor.

9. Control mechanism for hydraulic apparatus of the type having areversible fluid motor with a movable element, a source of fluidpressure and a reversing valve between said pressure source and saidfluid motor comprising electro-responsive means for actuating said valveto cause the operation of said fluid motor in one direction; relay meansfor controlling the flow of electric energy from a source to saidelectro-responsive means; switch means connected with said relay meansand perative to initially energize said relay to start the flow ofelectric energy to said electro-responsive means and the operation ofsaid fluid motor in said one direction; an electronic switch means forcontrolling the current supply for said relay means; and meanselectrically connected with said electronic switch means and responsiveto the movement of the movable element of said fluid motor whenoperating in said one direction to place said electronic switch incondition to direct current from the source to said relay means.

10. Control mechanism for hydraulic apparatus of the type having areversible fluid motor, a source of fluid pressure and a reversing valvebetween said pressure source and said fluid motor comprisingelectro-responsive means for actuating said valve to cause the operationof said fluid motor in one direction; relay means for controlling theflow of electric energy from a source to said electroresponsive means;switch means for initially energizing said relay means to start the flowof electric energy to said electro-responsive means and the operation ofsaid fluid motor in said one direction; an electronic switch means forcontrolling the current supply for said relay means; and currentgenerating means actuated by said fluid motor to energize saidelectronic switch means and place the same in condition to directcurrent from the source to said relay means.

11. Control mechanism for hydraulic apparatus of the type having areversible fluid motor, a source of fluid pressure and a reversing valvebetween said pressure source and said fluid motor comprisingelectro-responsive means for actuating said valve to cause the operationof i said fluid motor in one direction; relay means for controlling theflow of electric energy from a source to said electro-responsive means;switch means for initially energizing said relay means to start the flowof electric energy to said electro-responsive means and the operation ofsaid fluid motor in said one direction; an electronic switch means forcontrolling the current supply for said relay means; a coil supportedadjacent said fluid motor and connected in they circuit for saidelectronic switch means; and a magnetized element moved by said fluidmotor relative to said coil to generate current therein and cause theexcitation of said electronic switch means to place the same incondition to direct current from the source to said relay means. 7

12. In a hydraulic apparatus, areversible fluid motor having a movableelement; a source of fluid pressure; a control valve mechanism betweensaid pressure source and said motor; solenoid means for actuating saidcontrol valve mechanism to cause said motor to operate in a certaindirection; a second means for actuating said control valve mechanismwhen said solenoid is deenergized to cause said motor to operate in areverse direction; relay means for controlling the flow of electricenergy from a source to said solenoid means; and current generatingmeans operated by the movable element of said motor during operation insaid certain direction to maintain said relay in condition to directcurrent to said solenoid and retain said valve mechanism in position tocause said motor to continue to operate in said certain direction, saidrelay interrupting current flow to said solenoid when the currentgenerating means becomes inoperative due to the cessation of motion ofthe movable element of said fluid motor, said second means thenoperating said valve mechanism to reverse the operation of said fluidmotor.

References Cited in the tile of this patent UNITED STATES PATENTS1,927,583 Ernst Sept. 19, 1933 2,423,446 Grant July 8, 1947 2,451,263Webb Oct. 12, 1948 FOREIGN PATENTS 421,029 Germany Nov. 4, 1925

